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We establish a fixed-point theorem for the face maps that consist in deleting the $i$th entry of an ordered set. Furthermore, we show that there exists random finite sets of integers that are almost invariant under such deletions.…

Group Theory · Mathematics 2026-04-01 Tom Hutchcroft , Nicolas Monod , Omer Tamuz

We consider linear groups and Lie groups over a non-Archimedean local field $\mathbb F$ for which the power map $x\mapsto x^k$ has a dense image or it is surjective. We prove that the group of $\mathbb F$-points of such algebraic groups is…

Group Theory · Mathematics 2021-03-12 Arunava Mandal , C. R. E. Raja

We give a new, geometric proof of the section conjecture for fixed points of finite group actions on projective curves of positive genus defined over the field of complex numbers, as well as its natural nilpotent analogue. As a part of our…

Algebraic Geometry · Mathematics 2013-09-02 Ambrus Pal

We give a geometric characterization of finite rational groups. In particular, we prove that a finite group is rational if and only if there exists a finite geometry $\Gamma$ of type $I$ and action of $G$ on $\Gamma$ as a group of…

Group Theory · Mathematics 2019-05-29 Cecil Andrew Ellard

Given an action by a finite quantum group $\mathbb{G}$ on a von Neumann algebra $M$, we prove that a number of familiar $W^*$ properties are equivalent for $M$ and the fixed-point algebra $M^{\mathbb{G}}$ (i.e. hold or not simultaneously…

Operator Algebras · Mathematics 2025-04-22 Alexandru Chirvasitu

We prove a local-to-global result for fixed points of groups acting on affine buildings (possibly non-discrete) of types $\tilde{A}_2$ or $\tilde{C}_2$. In the discrete case, our theorem establishes the corresponding special cases of a…

Group Theory · Mathematics 2022-12-07 Jeroen Schillewaert , Koen Struyve , Anne Thomas

We give necessary and sufficient conditions for a function in a naturally appearing functional space to be a fixed point of the Ruelle-Thurston operator associated to a rational function, see Lemma 2.1. The proof uses essentially a recent…

Dynamical Systems · Mathematics 2020-07-23 Genadi Levin

The main goal of this paper is to obtain a formula for the T-equivariant Riemann-Roch number of certain G-spaces which are the finite dimensional models of certain infinite dimensional spaces with Hamiltonian LG-actions, here T is a maximal…

Algebraic Geometry · Mathematics 2007-05-23 Sheldon X. Chang

A group of bijections G acting on a set X is said with fixed points (abbreviated as gaf from the french "groupe {\`a} points fixes") if any element of G has at least one fixed point in X. The G group is said with a common fixed point…

Group Theory · Mathematics 2019-01-28 Guido Ahumada , Bernard Brighi , Nicolas Chevallier , Augustin Fruchard

In previous work, all finite simple groups that act with fixity 4 have been classified. In this article we investigate which ones of these groups act faithfully on a compact Riemann surface of genus at least 2 with fixity four in total and…

Group Theory · Mathematics 2026-03-17 Patrick Salfeld , Rebecca Waldecker

In this article we discuss a possibility to implement a well-known scheme of proof for contraction mapping theorems in a situation, when convergence, families of Cauchy sequences, and contractiveness of mappings are defined axiomatically.…

Functional Analysis · Mathematics 2023-07-13 Vladyslav Babenko , Vira Babenko , Oleg Kovalenko

Consider the following property of a topological group G: every continuous affine G-action on a Hilbert space with a bounded orbit has a fixed point. We prove that this property characterizes amenability for locally compact sigma-compact…

Group Theory · Mathematics 2015-08-12 Maxime Gheysens , Nicolas Monod

We prove that if $F$ is a finitely generated abelian group of orientation preserving $C^1$ diffeomorphisms of $R^2$ which leaves invariant a compact set then there is a common fixed point for all elements of $F.$ We also show that if $F$ is…

Dynamical Systems · Mathematics 2007-05-23 John Franks , Michael Handel , Kamlesh Parwani

We show that every real analytic action of a connected supersoluble Lie group on a compact surface with nonzero Euler characteristic has a fixed point. This implies that E. Lima's fixed point free $C^{\infty}$ action on $S^2$ of the affine…

Dynamical Systems · Mathematics 2007-05-23 Morris W. Hirsch , Alan Weinstein

Fixed point results with respect to generalized rational contractive mappings in semi-metric spaces endowed with a directed graph are proved. Some examples are provided to illustrate the results. The obtained results extend, improve and…

General Topology · Mathematics 2023-08-04 Talat Nazir , Zakaria Ali , Shahin Nosrat Jogan , Sergei Silvestrov

Let F be a non-archimedean local field of characteristic zero whose residue field has at least three elements. Let G be an almost simple linear algebraic group over F, with rank_F(G) >= 2. Let X be a simply connected symmetric space of…

Group Theory · Mathematics 2026-04-17 Federico Viola

We explain, following Gromov, how to produce uniform isometric actions of groups starting from isometric actions without fixed point, using common ultralimits techniques. This gives in particular a simple proof of a result by Shalom:…

Group Theory · Mathematics 2010-01-29 Yves Stalder

In this article, we prove the existence of common fixed points for a pair of maps on a $q$-spherically complete $T_0$-ultra-quasi-metric space. The present article is a generalization, in the assymmetric setting of the paper of Rao et…

General Topology · Mathematics 2014-12-04 Collins Amburo Agyingi , Yaé Ulrich Gaba

The aim of this note is to give an easy example of a finitely presented group that cannot act without a fix point on a CAT(0) space of finite dimension. Such an example has been recently constructed by Arjantseva et al., using other…

Group Theory · Mathematics 2009-01-13 Indira Chatterji , Martin Kassabov

Given an action of a Compact Quantum Group (CQG) on a finite dimensional Hilbert space, we can construct an action on the associated Cuntz algebra. We study the fixed point algebra of this action, using Kirchberg classification results.…

Operator Algebras · Mathematics 2012-10-23 Olivier Gabriel